Various forms of filtration and compaction equipment have been devised but in general these have included either many moving parts or a fixed system both of which have worked in a batch compaction mode. That is, a batch of slurry to be dewatered is fed into a chamber and then a piston may compact the slurry with water escaping through a screen to produce a wad or block of dewatered waste which is then removed. The limitation on this process is that it is non-continuous and hence not applicable for industrial application. There is a high wear because of the piston travel past an inlet port and also wear within the chamber and hence particularly abrasive slurries can wear such a chamber out in very short time. There may also be a slow compaction rate which will again reduce the usefulness of such a process.
It is the object of this present invention to provide a more continuous process for the dewatering of slurries and the like either for producing a desirable product from the solids in the slurry or to clean a filtrate.
To look at one example it is possible to produce slurries of waste paper fibres and to dewater these for subsequent formation into desirable products such as wood substitutes for many applications. In this case it is the solids product which is the desirable product.
To look at another example, in the asbestos removal industry for instance, considerable amounts of liquids contaminated with asbestos fibres are produced and these wastes are difficult to dispose of unless the fibrous material can be extracted from the liquid. The fibres may be a very low concentration in the liquid but all of the liquid must be filtered. Similarly in the paper making industry, paper fibres remain in the waste waters and these should be removed before the waste waters are disposed of. There are examples where the desirable product is a clean filtrate.
The invention, however, is not restricted to the removal of fibrous materials from slurries but may also be used for the removal of particulate materials such as clays, diatomaceous earths and the like from water.
It is the object of this invention therefore to provide a continuous compaction arrangement to seperate liquids from solids when these are in the form of slurries.
It is also to be realised that this invention is directed towards systems in which it is desirable to remove waste water from a wanted dewatered as much as it is for the removal of unwanted dewatered solids from a desirable liquid. An example of the former may be the removal of a desired precipitate from a chemical solution where a continuous process is desirable and an example of the latter may be the extraction of fruit juice from fruit juice pulp.